The animal cell is derived from the plant cell. This assumption of scientists is based on observations of Euglena Zelena. In this unicellular, the features of an animal and a plant are combined. That's why Euglena considered a transitional stage and confirmation of the theory of the unity of all living things. According to this theory, man originated not only from monkeys, but also from plants. Shall we push Darwinism into the background?
Description and features of Euglena
In the existing classification Euglena Zelena refers to unicellular algae. Like other plants, the unicellular plant contains chlorophyll. Accordingly, in signs of Euglena Zelena includes the ability to photosynthesis - the conversion of light energy into chemical. This is typical for plants.
The structure of Euglena Zelena suggests the presence of 20 chloroplasts in the cell. It is in them that chlorophyll is concentrated. Chloroplasts are green plates and are found only in cells with a nucleus in the center. Sunlight feeding is called autotrophic. Euglena uses such during the day.
The structure of Euglena Zelena
The tendency of unicellular organisms to light is called positive phototaxis. At night, the alga is heterotrophic, that is, it absorbs organic matter from the water. The water must be fresh. Accordingly, Euglena is found in lakes, ponds, swamps, rivers, preferring polluted ones. In reservoirs with clean water, algae are few in number or completely absent.
Living in polluted water bodies, Euglena Zelenaya can be a carrier of trypanosome and Leishmania. The latter is the causative agent of a number of skin diseases. Trypanosomes also provoke the development of African sleeping sickness. It affects the lymphatic, nervous system, and leads to fever.
We have to pickle domestic reservoirs with chemicals, while transplanting fish into other containers. However, some aquarists consider the heroine of the article as food for fry. The latter perceive Euglene as animals, noticing active movement.
As food for fry, euglena is propagated at home. Do not go to the pond all the time. Protozoa multiply quickly in any dish with dirty water. The main thing is not to remove dishes from daylight. Otherwise, the process of photosynthesis will stop.
Heterotrophic nutrition, to which Euglena resorts at night, is a sign of animals. Other animal features of the unicellular species include:
- Active movement. Euglena Green's cage has a flagellum. Its rotational movements provide the mobility of the algae. It moves progressively. This is different Euglena Green and Infusoria Shoe... The latter moves smoothly, having many cilia instead of one flagellum. They are shorter and wavy.
- Pulsating vacuoles. They are like muscle rings.
- Mouth funnel. As such, Euglena does not have a mouth opening. However, in an effort to capture organic food, the unicellular, as it were, presses inward a part of the outer membrane. Food is retained in this compartment.
Given that Green Euglena has signs of both plants and animals, scientists argue about the belonging of the heroine of the article to a certain kingdom. The majority for the reckoning of Euglena to the flora. A single-celled animal is considered by about 15% of scientists. Others see Euglene as an intermediate form.
Signs of Euglena Zelena
The unicellular body has a fusiform shape. He has a tough shell. The body length is close to 0.5 millimeters. In front of Euglena's body is dull. There is a red eye here. It is photosensitive and allows the unicellular to find "feeding" places during the day. Due to the abundance of eyes in places where Euglene accumulates, the surface of the water looks reddish, brown.
Euglena Green under the microscope
A flagellum is also attached to the anterior end of the cell body. Newborn individuals may not have it, since the cell divides in two. The flagellum remains on one of the parts. On the second, the motor organ grows over time. Rear end of the body Euglena Green plant has a pointed. This helps the algae to screw into the water, improves streamlining, and therefore speed.
The heroine of the article is characterized by metabolism. It is the ability to change the shape of the body. Although it is often spindle-shaped, it can be:
- like a cross
- rolling
- spherical
- lumpy.
Whatever form Euglena is, her flagellum is not visible if the cell is alive. The process is hidden from the eyes due to the frequency of movement. The human eye cannot catch it. The small diameter of the flagellum also contributes to this. You can examine it under a microscope.
Euglena's structure
To summarize what was said in the first chapters, Euglena Green - animal or plants consisting of:
- Flagellum, the presence of which assigns Euglena to the class of flagellates. Its representatives have from 1 to 4 processes. The flagellum diameter is approximately 0.25 micrometers. The process is covered with a plasma membrane and is composed of microtubes. They move relative to each other. This is what causes the general movement of the flagellum. It is attached to 2 basal bodies. They keep the fast flagellum in the cytoplasm of the cell.
- Peephole. It is also called stigma. Contains optic fibers and lens-like formation. Due to them, the peephole catches the light. Its lens reflects onto the flagellum. Receiving an impulse, he begins to move. Red organ due to colored drops of lipid - fat. It is colored with carotenoids, in particular, hematochrome. Organic pigments of orange-red tones are called carotenoids. The ocellus is surrounded by a chloroplast-like membrane.
- Chromatophores. This is the name of the pigmented cells and components of plants. In other words, we are talking about chlorophyll and chloroplasts containing it. Taking part in photosynthesis, they produce carbohydrates. Accumulating, the latter can overlap chromatophores. Then Euglena becomes whitish instead of green.
- Pellicula. Consists of flat membrane vesicles. They compose the protozoan integumentary film. By the way, in Latin pillis is leather.
- Contractile vacuole. Located below the base of the flagellum. In Latin, vacuole means hollow. Similar to a muscular system, the system contracts, pushing excess water out of the cell. Due to this, a constant volume of Euglena is maintained.
With the help of the contractile vacuole, not only is the expulsion of metabolic products, but also respiration. Their system is similar Euglena Zelena and Amoeba... The core of the cell is the nucleus. It is displaced to the posterior end of the algae body, suspended on chromatin filaments. The nucleus is the basis of division, which reproduces Euglena Green. Class the simplest is characterized by just this way of reproduction.
The liquid filling of the Euglena cell is the cytoplasm. Its basis is hyaloplasm. It consists of proteins, polysaccharides and nucleic acids. It is among them that starch-like substances are deposited. The ingredients literally float in the water. This solution is the cytoplasm.
The percentage composition of the cytoplasm is unstable and devoid of organization. The visual filling of the cell is colorless. Euglene is colored exclusively by chlorophyll. Actually, the cytoplasm is limited by its clusters, the nucleus and the membrane.
Nutrition
Euglena Zelena's nutrition not only half autotrophic, but half heterotrophic. A suspension of a starch-like substance accumulates in the cytoplasm of the cell. This is a nutritional reserve for a rainy day. The mixed type of food is called mixotrophic by scientists. If Euglena gets into water bodies hidden from light, for example, cave ones, it gradually loses chlorophyll.
Then the unicellular algae begins to look more like the simplest animal, feeding exclusively on organic matter. This once again confirms the possibility of a relationship between plants and animals. In the presence of lighting, the heroine of the article does not resort to "hunting" and is inactive. Why wave a flagellum if food in the form of light falls on you by itself? Euglena begins to move actively exclusively in twilight conditions.
Algae cannot do without food at night, since it is microscopic. There is simply nowhere to make sufficient reserves of energy. The accumulated money is immediately spent on life processes. If Euglena is starving, experiencing both a lack of light and a lack of organic matter in the water, she begins to consume a starch-like substance. It is called paramil. Animals also use fat stored under the skin.
To a backup power supply protozoan Euglena Green resorts, as a rule, in a cyst. It is a hard shell that the algae forms when compressed. The capsule is like a bubble. Actually, the concept of "cyst" is translated from Greek.
Before cyst formation, the alga discards the flagellum. When unfavorable conditions give way to standard conditions, the cyst germinates. One Euglena may come out of the capsule, or several already. Each grows a new flagellum. During the day, Euglens rush to the well-lit areas of the reservoir, keeping to the surface. At night, unicellular organisms are distributed over the entire area of a pond or river backwater.
Organoids of Euglena Green
Permanent and specialized structures are called organoids. These are found in both animal and plant cells. There is an alternative term - organelles.
Organoids of Euglena Green are, in fact, listed in the chapter "Building". Each organelle is a vital element of the cell, without which it cannot:
- multiply
- carry out the secretion of various substances
- synthesize something
- generate and convert energy
- transfer and store genetic material
Organelles are characteristic of eukaryotic organisms. These necessarily have a core and a shaped outer membrane. Euglena Zelenaya fits the description. Generally speaking, eukaryotic organelles include: endoplasmic reticulum, nucleus, membrane, centrioles, mitochondria, ribosomes, lysosomes, and the Golgi apparatus. As you can see, the set of Euglena's organelles is limited. This indicates the primitiveness of the unicellular.
Reproduction and life expectancy
Reproduction of Euglena Zelena, as said, begins with nuclear fission. Two new ones diverge on opposite sides of the cage. Then it begins to divide in the longitudinal direction. Cross division is not possible. Euglena Zelena's break line runs between the two cores. The divided shell, as it were, is closed on each half of the cell. It turns out two independent ones.
While longitudinal division is taking place, a flagellum grows on the "tailless part". The process can take place not only in water, but also in snow, on ice. Euglena is tolerant of the cold. Therefore, blooming snow is found in the Urals, Kamchatka, and the Arctic islands. True, it is often scarlet or dark. The relatives of the heroine of the article - Red and Black Euglena - serve as a kind of pigment.
Euglena Zelena division
The life of Euglena Zelena is, in fact, endless, since the unicellular reproduces by fission. The new cell is part of the old one. At the same time, the first continues to "give" offspring, remaining itself.
If it speaks about the lifespan of a particular cell, which retains its integrity, we are talking about a couple of days. Such is the age of most unicellular organisms. Their lives are as small as their size. By the way, the word "Euglena" is composed of two Greek words - "eu" and "glene". The first is translated as "good" and the second is "shiny dot". In the water, the algae really shines.
Along with other protozoa, Euglena Zelenaya goes to the school curriculum. Single-celled algae are studied in the 9th grade. Teachers often give children the standard version that Euglena is a plant. Questions about him are found in the exam in biology.
One can prepare for both botany and zoology textbooks. Both have chapters dedicated to Euglene Zelena. Therefore, some teachers teach children about the duality of the unicellular. Especially often an in-depth course is given in specialized biochemical classes. Below is a video about Euglene Zelena, who scares the ciliates of shoes.
A. flagellates
B. cilia
B. pseudopods G. jointed limbs
6.Mushrooms are united with plants:
A. immobility
B. the presence of cell walls
B. apical growth G. immobility, presence of cell walls, apical growth
7.Mushrooms are united with animals:
A. the presence of chitin,
B. heterotrophic nutrition
B. the presence of a reserve substance - glycogen D. the presence of chitin, heterotrophic nutrition, the presence of a reserve substance - glycogen
8. Mushrooms that do not form mycelium:
A. mold
B. lamellar
B. yeast
G. tubular
A. smut B. tinder
B. ergot G. powdery mildew
10. The main features of plants are:
A. immobility, autotrophy, unlimited growth
B. mobility, autotrophy, unlimited growth
B. immobility, heterotrophy, unlimited growth G. mobility, heterotrophy, limited growth
11. The appearance of tissues and organs in plants is associated with:
A. land reclamation by plants
B. assimilation by plants of the aquatic environment
C. adaptations to photosynthesis G. global climate change
12. Bryophytes lack true:
A. stems B. roots
B. leaves G. stems, roots, leaves
13. Ferns are plants:
A. trees and shrubs
B. shrubs and perennial grasses
B. trees and perennial grasses D. shrubs and annual grasses
15. During the reproduction of the pine, the following propagation occurs:
A. fruits V. zarostkov
B. Semyan G. dispute
16. The vegetative organs of angiosperms are:
A. root, stem, leaf B. fruit
B. flower G. root, stem, leaf, flower
From the air into the cells of the leaf for respiration comes:
A. water B. carbon dioxide
B. oxygen D. nitrogen
From the air into the cells of the leaf for photosynthesis comes:
A. water B. carbon dioxide
B. oxygen D. nitrogen
19. Most of the water absorbed by the plant:
A. evaporates
B. is stored in the roots
V. is stored in the stem of G. is consumed in the process of photosynthesis.
Vegetative propagation of plants is carried out:
A. using dispute
B. using gametes
V. with the help of plant organs (root, stem, leaves, shoots) and their modifications G. by cell division by mitosis
The shank is:
A. flower base
B. stem-shaped part of the leaf
B. base of the fetus D. a segment of any vegetative organ
22. Of the above, only animals are characterized by:
A. cellular structure B. the presence of a nervous system
B. heterotrophic nutrition D. unlimited growth
In animal cells there is no:
A. core B. cellulose casing
B. Golgi apparatus D. cell center
By the way of feeding, animals belong to organisms:
A. phototrophic B. heterotrophic
B. autotrophic G. chemotrophic
The anterior section of the alimentary canal of animals, located behind the oral cavity, is called:
A. goiter B. esophagus
B. pharynx G. appendix
26. The body of the molluscs is covered with:
A. mantle B. sink
B. chitin G. cocoon
27. The sexual process is:
A. fusion of sperm and egg
B. formation of germ cells
B. introduction of a virus into a cell D. exchange of genetic information between individuals of the same species
Amphibians are otherwise called:
A. lung-breathing C. reptiles B. amphibians D. tadpoles
29. The largest living lizard is:
A. spindle B. gecko B. viviparous G. monitor lizard from Komodo island
30. A distinctive feature of birds from reptiles is:
A. periodic molting C. egg-laying B. dry skin D. missing teeth
31. Mammals are so called because:
A. have mammary glands
B. feed on milk
B. feed the young with milk D. have mammary glands and feed the young with milk 32. During life, organisms undergo a number of quantitative and qualitative changes, which are called:
A. self-regulation B. growth and development B. reproduction D. metabolism
33. The unit of development of living organisms is:
A. cell C. organ B. tissue D. organ system
Arrange the organisms so that they form a food chain:
A) apple blossom beetle, b) apple tree, c) flycatcher, d) falcon
1) a --- b --- c ---- d 3) d --- c --- a --- b
2) b --- a --- d ---- c 4) b --- a --- c --- d
35. The relationship between organisms at the community level studies:
A. biophysics C. biotechnology B. biocenology D. molecular biology
Euglena green (Euglena viridis) is a unicellular protozoan of the genus Euglena of the flagellate class of the sarcomastigophora type. According to zoologists, green euglena is included in the group of animals - plant flagellates (phyto-flagellates). Other scientists believe that green euglena is a widespread representative of euglena algae in nature.
These protozoa live in heavily polluted water bodies - ditches, swamps, puddles, shallow decaying fresh water bodies. Sometimes euglena green is found in clean water bodies, both fresh and salty.
The name Euglena was given for the green color that chromatophores give to the body. If we look at the green euglena under a microscope, it is noticeable that the green euglena cell has a fusiform oblong shape, its size is smaller than that of the common amoeba (0.05-0.06 mm). Under the envelope is the cytoplasm with organelles and one large nucleus. The outer layer of the cytoplasm is compacted, due to which the shape of the cell can change only within certain limits - slightly shrink, while the cell becomes slightly shorter and wider. In the body of an individual, a red light-sensitive ocellus is clearly visible at its front edge. Next to it, in a depression, there is a flagellum, with the help of the rotational movements of which the green euglena moves. A contractile vacuole adjoins the light-sensitive eye, its main function is osmoregulatory (release of the body from excess water). Chromatophores in the body of an individual are oval in shape and are located radially.
A feature of green euglena is that in its structure and life, the features of both a plant and an animal are combined. This indicates the common origin of plant and animal organisms in the process of evolution. So, euglena is characterized by mixotrophic nutrition, that is, it is capable of autotrophic and heterotrophic nutrition due to the presence of chloroplasts with chlorophyll in the cell. Photosynthesis is carried out under good illumination conditions in chloroplasts. But when euglena is green for a long time in places with poor lighting, its cell seems to "discolor" due to the destruction of chlorophyll in chloroplasts. Euglena becomes pale green or transparent. The simplest goes to a heterotrophic type of nutrition, absorbing organic substances dissolved in water. When euglena gets into illuminated places, all processes of autotrophic nutrition are restored.
In the light, as a result of photosynthesis in the body of green euglena, a reserve nutrient is formed, which is similar in structure to starch. This substance is deposited in the form of grains in the cytoplasm of the cell.
Thus, in the body of green euglena, such functions as nutrition, respiration, excretion, photosynthesis, and reproduction are carried out. The reproduction of organisms of this type of euglena is asexual - by dividing the cell in half, in contrast to the ciliate-shoe, which is also characterized by the sexual process. With the rapid reproduction of a huge number of individuals of green euglena, brown, red or green "blooming" of water bodies is observed.
The world of living organisms on our planet is obscenely diverse, because nature has managed to create a huge number of very different creatures, differing both in size and in more conceptual details. One of these creatures, the existence of which many do not even know, is the green euglena - small unicellular organism, information about which is much more interesting than it might seem at first glance.
What is green euglena?
Scientifically speaking, this microorganism is euglenozoa from the protist species. Agree that such a description is unlikely to say anything to the majority of people ignorant of biology. Therefore, it makes sense to give a description that is more accessible to the broad masses, and it will sound like this: green euglena is a unicellular microorganism, which has a length of about 60 micrometers, the cell of which has a nucleus. Reproduction occurs due to longitudinal cell division asexually.
Such a "dry" description also does not give us a complete understanding of why this microorganism deserves such attention. In order to appreciate all the unusualness and intricacy of the green euglena, it is worth considering a few more aspects of its life.
Habitat
Traditionally, this type of euglena lives in such a rich variety of protozoa and unicellular places such as swamps, ditches and other dirty bodies of water. Nevertheless, there is a very high probability of settlement of this microorganism in clean water, however, such a habitat, although acceptable, has a number of properties negative for euglena, which we will consider in more detail in the section on its nutrition.
The structure of euglena green
Like any other unicellular, the structure of the green euglena is not particularly complex. It includes:
Let's consider these points in a little more detail: on the outside, this organism has a thin membrane that hides the cytoplasm - the interior of the cell, which contains its nucleus, as well as organelles - a kind of analogue of internal organs.
The cytoplasm of green euglena is quite dense, but nevertheless plastic, which allows the cell to change its shape within small limits, in particular, it able to lengthen and contract... This property, along with the presence of a flagellum, allows this microorganism to move in its characteristic environment.
If you look closely at this type of euglena, you can find it has a small "eye" that reacts to light. This elementary organ of vision allows a microorganism to have basic spatial orientation abilities.
However, of greatest interest is the presence of unicellular chloroplasts and chromatophores in this single cell. Thanks to them, or rather? chlorophyll present in chloroplasts, this type of euglena got its name.
This small unicellular species belongs to the so-called mixotrophs - organisms capable of using several sources for energy. Under normal conditions, the main consumed "product" of euglena is sunlight, which interacts with the chlorophyll contained in it. This way of eating is called autotrophic and implies the absence of external intake of nutrients.
However, if the green euglena remains in the dark for too long, then extremely interesting metamorphoses take place with it. First of all, it changes its color - gradually losing its green color, this microorganism becomes transparent in the literal sense of the word and, in order to somehow maintain its vital activity, switches to a heterotrophic type of nutrition, which implies the absorption of organic microelements from the environment. However, if the habitat of euglena is a clean reservoir, then micronutrient deficiencies can lead to a reduction in its population.
If the conditions become completely hostile (the reservoir dries up or freezes), then this microorganism has no choice but to "turn" into a cyst - to discard the flagellum and grow a dense protective membrane, which will persist until more favorable conditions arise.
Green euglena as proof of the theory of evolution
Traditionally, we are used to dividing the organisms around us into flora and fauna. Each of these categories has certain qualities:
- Food method;
- Breeding method;
- A way of moving in space.
The uniqueness of green euglena lies in the fact that it combines the qualities of both plants and more "mobile" living organisms. Under favorable conditions, it behaves like a typical plant - it practically does not move and receives nutrients through photosynthesis. But as soon as the environment becomes less friendly, this tiny organism turns into a mobile creature that is forced to move in space in search of food.
The fact that such a "universal" organism exists is a great proof of the existence of a common ancestor, both in plants and in animals. It can be easily concluded that evolution has evolved along two paths - some organisms over time preferred to continue to receive and accumulate energy from the sun's rays, while others have learned to consume a variety of organics in order to prolong their existence.
Euglena green is a unicellular creature belonging to plant flagellates. Euglena has an elongated body shape, and the back is pointed.
Its size ranges from 50-60 micrometers, and its width is about 14-18 micrometers. The body is mobile, if necessary, the euglena shrinks or becomes wider.
The structure of euglena green
On top of euglena green is covered with a thin layer of cytoplasm, this elastic substance is called pellicle, it performs a protective function. In the front of the body there is one tourniquet, when the euglena moves it, it moves forward. The base of the tourniquet is thickened; an eye spot is located on it.
Euglena was named green due to the color of her body - a green tint is given to the cell by chromatophores. The chromatophores are oval in shape, they are located in the euglena in the form of a star, the process of photosynthesis is carried out in them. In the light, carbohydrates are formed, they look like colorless grains. Sometimes carbohydrates are formed so much that they block the chromatophores, then the body of the euglena becomes whitish. In the dark, the process of photosynthesis does not take place. The cell begins to digest the supply of carbohydrate grains, at which point it turns green again.
These creatures inhabit polluted waters with a high content of organic matter. In connection with these euglena greens have two types of food: they eat both plant foods and animals. That is, on the one hand, green euglena can be attributed to plants, and on the other hand, to animals. This cell has a mixed structure, which causes a lot of controversy among modern scientists. Botanists believe that green euglena is a plant, and zoologists attribute it to the flagellate subtype.
Certain representatives of euglena, which are the closest relatives of euglena green, cannot participate in photosynthesis at all, their way of feeding is completely like that of animals. These types include, for example, astasia. In such representatives of the order of Euglena, complex mouthpieces are formed, which are necessary for absorbing small food particles.
Green euglena movement
Euglena is an animal with flagella. Not all species move with flagella. Some species move by contracting the body and performing wave-like movements. How the process of this kind of movement occurs is not fully understood. Under the shell of euglena are protein ribbons arranged in a spiral. These ribbons are cutting. It is believed that the organelles that provide the cell with energy and the contractile filaments are interconnected. But contractile movements can be associated with mucus secreted through the excretory canal.
How green euglena reproduce
Under favorable conditions, green euglena actively reproduce. In this case, in one day, the clear water in the pond becomes cloudy, brownish or greenish in color. If you examine a drop of such water under a microscope, then a huge amount of euglena will float in it.
The closest relatives of green euglena are snow euglena and bloody euglena. When these types of euglena are actively developing, amazing things happen, for example, Aristotle observed the formation of "bloody" snow in the 4th century. Darwin encountered a similar phenomenon when he traveled on the Beagle.